A fuel tank of the above kind is often used as the fuel tank for an outboard engine. A main fuel such as kerosene or alcohol is interchangeably used together with an auxiliary fuel such as gasoline which has better ignitability and vaporizability than the main fuel. A fuel tank of this kind according to the prior art has its inside divided by means of a partition arranged in the tank body to form upper and lower compartments for respectively reserving the different kinds of fuels. However, since a fuel tank of this kind has its partition welded to the tank body, it has disadvantages in that the portions to be welded are complicated, that a rust preventing agent is melted by the welding heat thereby to reduce the corrosion resistance, and that a stress corrosion caused by the residual stress is liable to occur.
The present invention has been conceived in view of the background thus far described and comtemplates to provide a fuel tank which has its inside divided into a plurality of compartments without any use of welding, thereby to eliminate the corrosion resistance due to the welding process where welding otherwise would have been used.